Circuit breaker



jmfiyw, 1942 L. @GLDBERG CIRCUIT BREAKER Filed Julyl'l, 1940 2 Sheets-Sheet l Inventor:

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y 28, 1942- L. J. GOLDBERG dx 'fi fi fi CIRCUIT BREAKER Filed July 17, 1940 2 Sheets-Sheet 2 Imvevmtor: eon J. Gol cLbercg,

Patented July 28 1942 CIRCUIT BREAKER Leon J. Goldberg, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application July 17, 1940, Serial No. 345,969

2 Claims. (Cl. 200llli) My invention relates to circuit breakers, more particularly to electromagnetically operated circuit breakers or contactors, and has for its object a circuit breaker having compactness, accessibility of parts for removal and maintenance, long life and economy of manufacture.

For a more complete understanding of my invention, reference should be had to the accompanying drawings in which' Fig. 1 is a fragmentary plan view of a contactor embodying my invention; Fig. 2 is a side elevation view of the device shown in Fig. 1 looking toward the right hand; Fig. 3 is a fragmentary view in section taken along the line 33 of Fig. 1 looking in the direction of the arrows; Fig. 4 is a view mainly in section taken along the line- 4-% of Fig. 1 looking in the directiofi of the arrows; Fig. 5 is a fragmentary view of the arc chute and insulating base; Fig. 6 is an exploded view of the stationary contact and blow-out coil assembly; Fig. 7 is a view in perspective of the stationary magnet core, and shading coils disassembled therefrom; Fig. 8 is a fragmentary side elevation view showing the movable contacts turned to permit removal of the stationary contact; Fig. 9 is an elevation view of an arc chute provided with a modified form of my invention; while Fig. 10 shows the core of the blowout coil.

Referring to the drawings, in one'form of my invention, the switch parts are mounted on a steel base plate it which can be secured upright to a suitable panel or other support. A stationary magnet frame M (Fig. 7) is secured by brackets l2 and it to the'support it by means of suitable screws (not shown) a layer of electrically insulating material (not shown) being provided between the brackets i2 and iii and the support and the screws being electrically insulated from the support. Also secured directly to the support it is a base member it (Fig. 5), made of a suitable electrically insulating material such as a molded phenolic condensation product, having its right-hand side, as seen in Fig. l, secured to the plate it over the bracket it by means of a bolt l5 passing through the two parts. A spring clamp iii (Fig. 3) is provided underneath the head of the bolt to takeup irregularities in it? or Hi instead of allowing either ill or M to bend to compensate for these irregularities. One other bolt, not shown, near the left hand side of M is also provided to secure the supports it and M rigidly together, a layer of insulating material ll being provided between them. On its side adjacent the support ill, the support. is provided with a ,large recess l9 inwhich lies the heads of screws or bolts hereinafter referred to in detail for securing various switch parts to the other side or front of the insulating base it, the layer of insulation it further insulating these heads from the metal support it.

As shown, the circuit breaker is a three-circuit device such as for a three-phase circuit, the details for one circuit only, i. e., one stationary and one movable contact, being shown in detail.

Each stationary contact (Fig. 8) is mounted on an electrically conducting, non-magnetic supporting member Eli, preferably made of copper, and secured thereto by means era-screw 22 passing through a slot in the end of the contact adjacent the insulating base i l. Preferably a boss (not shown) provided on the member 2i around the screw 22 for engaging a corresponding, recess on the contact it? so as to further position the contact.

As shown in Fig. l, the stationary contact supporting member is secured by screws 25 to the insulating base M. It is provided with a length 26 (Fig. 6) extending outward at right angles to the base and with a portion extending upward as seen in Fig. i and slightly curved back toward the base in conformity with the curvature of blow-cut coil 2i but spaced from the blow-out coil. This blow-out coil, mounted inside or behind the member 2i is formed from a strap of electrically conducting material, such as copper, which is wound. edgewise into a coil. (Zine end file ii) of thecoil is welded directly to the contact supporting member 26 while its other end is welded to a terminal strap 2% which is secured to the support it by a screw 29. A. magnet iron core extends axially of the blow out coil and pole piece plates 3% and 32 made of magnet iron are welded to the ends of this core. in the assembly of the plates 3i and 32,,they are bent or shaped to rest tightly against the edges or sides oi the supporting member 2i and are secured and pressed suitably in place while they are welded to the core member Sb.

Thus the blow-out coil ill, the core 3@, the pole pieces 3i and t2, and the support 25 are securely assembled together by welding into a unitary construction. The ends are and 3212 (Fig. 6) of the pole pieces project slightly beyond the member 25 at the lower end of the upright portion of the member 2i so as to bring the flux passing between these ends of the pole pieces in the region of the contact surface on the stationary contact it which lies between these projecting ends, as seen in Fig. 4. It will be noted, however, that the pole pieces extend upward, as

seen in Fig. 4, beyond the upper end of the stationary contact 23 but substantially flush with the outer surface of the member 3| so'as to form a magnetic field between the poles along the upper region of the member II. This magnetic field moves the end of the arc upward along the member II was to increase the length of the arc and tend to extinguish it. 4

A distinguishing feature of this assembly of the stationary contact, blow-out coil and other parts is its compactness, i. e. it is only slightly wider in a direction parallel with the axis of the core 33 than the width of the contact 33.

The movable contact. 33 (Fig. 4) which is a substantially straight strap of conducting material, such as copper, is mounted on an irregularly shaped rotatable member or shaft 34 having its ends plvotally mounted on metal supporting brackets 33 and 33 secured to the supporting plate l3. This rotatable shaft or member 34 is made of a suitable electrically insulating material, such as a molded phenolic resin. At each end, it is preferably provided with a tubular portion 33a (Fig. 8) fitting over a cylindrical bearing member 33b carried by the brackets 33 and 33 so as to support the member 34 for rotation about a predetermined axis parallel with the support It.

As shown in Fig. 4, the support 34 is provided with an arm or bracket 31 against which the movable contact 33 is pressed by a helical spring 33, the opposite end of the spring being secured tom cross bar 33 forming a part of the support 34. Also the bracket 31 is provided with a wedge shaped bearing projection 43 which engages a notch in the adjacent side of the contact 33 and forms a pivot bearing for the contact. The spring 33 bears on the contact on an area between the bearing 43 and the end 31a of the bracket 31 so as to hold the contact on the hearing which is adjacent the lower end of the contact, as seen in Fig. 4, and to press the contact against the end of the bracket 31, shown as a cross bar 31a forming a part of the supporting member 34. Preferably the upper end of the contact 33 is provided with a slightly curved contact making portion 4i which prevents making current on a sharp edge when 33 engages with 23.

The movable contact 33 is so mounted on the bracket 31 that the three points, its point of initial engagement with the stationary contact, its pivot on the bearing 43, and the center or axis 42 of the shaft 34 are on a straight line and lie in a common plane. With this arrangement, the two'contacts engage without sliding action, but when the movable armature 43 secured to the member 34. seats or seals on the stationary magnet core II, a slight sliding action is produced between the contacts. This minimum sliding action reduces the wear on the contacts rolls slightly on the stationary contact. This action minimizes bouncing of the contacts and thereby minimizes any tendency for the contacts to weld together during their enga ing. action. Also the lowering movement of the line of contact tends to break any incipient welds between the contacts. Moreover, by reason of the plane contacting surface of the stationary contact and the similar plane surface of the movable contact, except for the bend at the upper end of the movable contact, and the bend at the lower part of the stationary contact, the line of engagement between the two is given a maximum movement downward, as seen in Fig. 4.

Another feature,of the movable contact 33 is the extension 44 (Fig. 4) on its lower end below the pivot 43 which extension provides sufiicient mass to prevent vibration or bouncing of the movable contact during the opening movement. It will be understood that when the supporting member 34 is moved in a clockwise direction, as seen in Fig. 4, from the closed to the open position, the upper end or stop 31a of the bracket 31 strikes the movable contact a sharp blow, and because a considerable portion of the mass of the movable contact lies above the end of the bracket. there is a (tendency for the contact to turn in a counterclockwise direction about the upper end of the bracket as a pivot, the lower end leaving the bearing 43. Such action would result in wear on the bearing 43 and, moreover, produce irregular opening movement of the contact. It might even cause the movable contact to reengage the stationary contact after it has moved away slightly from the stationary contact. The

extra mass 44 of material on the lower end of the movable contact eliminates this irregular action by balancing the mass of the movable contact on each side of the upper end of the bracket 31 which engages the movable contact with a blow. In fact, this mass 44 tends to cause the movable contact to pivot about its bearing 43 when the blow is given it. The contact, therefore, does not leave its bearing and, moreover, the opening movement of its upper end is accelerated. This is a distinct advantage when the gap between the contacts is small for it overcomes the tendency for the arc to remain stationary and burn the contacts.

As seen in Figs. 1 and 3, the U-shaped magnet armature 43 is mounted on a channel shaped metal arm 43, the lower end of which is secured to the insulating shaft or support 34 by screws 43b. The-lower end 43 of the armature 43 exand prolongs their life. Also the small amount end slightly toward the movable contact. By

reason of this arrangement, the line of engagement between the two contacts starts near the upper ends of the two as they first touch and then moves downward as the movable, contact tends through an aperture 41 in the arm 43 and is provided with a slot 43 loosely embracing the lower-edge of the aperture. The upper end 43 of the armature extends through a slot between the sides of the arm 43. A second bearing for the armature in addition to that provided by the slot 43 is provided by an extruded rounded projection 43a on the arm 83 which engages the armature at a point equidistant from the armature pole faces. Movement of the armature on the arm 43 is, furthermore, limited in a clockwise direction, as seen in Fig. 3, about the bearing 434 by a bolt 33 extending between the sides of the arm 43, this bolt being surrounded by an insulating fiber cylinder 3| (Fig. 1) which is engaged by the upper end of the armature. The bolt 33 is also insulated from 43 at one end, thereby preventing 43 and 33 from forming a closed electric circuit around the armature. Aperture 4! extends to the end of 43 as shown by 41a, thereby preventing the lower part of 43 from forming aclosed electric circuit around the armature. Moreover, the, bolt 50 forms a stop to limit the clockwise movement of the support 34, the bolt coming to rest against an arm 52 secured to a strap 53, made of- .a non-magnetic material such as'brass, extending through guishing opening I! in which thearc is extinguished quickly.

the operating coil 54 and secured by a screw 55 to the stationary magnet core II.

This suspension for the armature 43 provided freedom for the armature to align itself on the pole faces of the stationary core regardless. of

- slight manufacturing inaccuracies in the support for the armature and the mounting of the stationary core. The armature is loosely supported at each end but with small clearances, which provides for a small amount of universal pivotal increment in the bearing projection 45a. -Moreover, the pole faces of the stationary core are located in a plane passing through the axis of rotation of the support 34 by reason of which sliding of the armature on the stationary core and resulting abrasive action is minimized. This sliding action is also minimized by the support for the armature at its lower end with slight clearances whereby the lower end is free to move but slightly toward the stationary core during the opening or closing movement. The weight of the armature is supported on the lowerwall of the aperture 41.

As shown in Fig. 3, the pole shader 56 on the upper leg of the magnet extends through the operating coil 54 and has a portion exterior of the coil substantially as large as the other portion. Also, as shown in Fig. 7, this exterior por-' tion 51 has a reduced cross section so that the preponderant amount of heat'is generated in this portion outside of the coil. It will be understood that the remaining portion of the shader inside the coil has a cross section too large to of the armature (striking the stationary core from being transmitted to the shader and breakage of the shader by metal fatigue. To further minimize the effect of these shocks, the shader is made of very light material such as aluminum or an aluminum alloy. The pole shader is furthermore secured byprojections 65 provided in it which projections lie in a notch 52 in the stationary core and are held therein by the strap 53 extending over the notch.

The pole shader 83 on the lower leg, which is not subjected to the severe shocks of the upper leg, extends toward the outside of the stationary core and lies in a notch 64. It is secured in this notch by a U-shaped spring 65 (Fig. 3) having its ends secured in holes 66 (only one of which is shown) in the supporting brackets l2 and I3.

A single piece molded arc chute 61 covers all three pairs of switch contacts including the blowout coils and blow-out pole pieces. This chute is molded from a suitable electrically insulating material such as an asbestos compound. As shown in Fig. 5, the arc chute is provided with chambers or recesses I58 which receive the pairs of switch contacts. Moreover, the insulating base I4 is provided-with walls 69 between the pairs of stationary contacts. These. walls dovetail in tightly fitting relation with the walls on the arc chute 51, dovetail joints I and Illa being provided. Also each recess 88 in the arc chute leads outward through a restricted arc extinthe slot. This arrangement prevents the shock It will be noted that the shaft or support 34 for the movable contact has no metal parts ad- Jacent the switch contacts and since the blowout coil and pole pieces 3| and 32 are confined substantially within the width of the stationary contact supporting members 2l,.the pole pieces and the members 2| are the electrically conducting parts nearest each other. Consequently the maximum insulating requirements are presented by these parts, which are completely electrically insulated by the walls 63 of the arc chute. Moreover, barriers 12, Figs. 1 and. 4, are provided onthe rotatable support 34 on each side of each movable contact 33. These barriers have edges 13 which are arcuate with the'axis of support 34 as a center and are in closely spaced relation with similar complementary arcuate edges 14 on the chute 61.

Also this rotatable member is provided with barriers 15 between the flexible conducting shunts 16 leading to the movable contacts.

As shown, in Fig. 4, the arc chute B1 is hung on an upper cross bar or ledge 11 forming an integral part of-the insulating base M. The are chute is provided with projections 18 which extend downward behind or on the right-hand side of the cross bar H as seen in Fig. 4 between this cross bar H and the upper, projecting end of the stationary contact supporting member 2 I.

Therefore, the arc chute can be slipped in place or removed very readily.

Provision is made for preventing the complete removal of the screws 22 (Fig. 8) from the member 2|. To provide access to the screw 22- for the removal or adjustment of the stationary contact, the member 34 is turned in a clockwise direction to the position shown in Fig. 8, the arc chute B'l having been removed and also the stop 52 for the armature. In this position of the member 34, a projection 19 on the member lies just behind the screw 22 so that the screw can be turned out only until its head engages the stop 19, as indicated in Fig. 8. This completely releases the stationary contact 20 but the screw remains in engagement and supported by the member 2!. This stop it prevents complete removal of the screw from the member 2! and thereby avoids loss of the screw and the tedious process of rethreading it in the member 24.

The flexible shunts it are made of braided copper wirebut for compactness instead of having terminals at each end, the ends are dipped in hot tin or solder to form solid terminals 76a and ltb. Also the terminal lfib (Fig. 4) is extended and turned back away from the movable contact M to form an arcing horn. When the switch is opened the arc is stretched between the upper end of the supporting member 2! and this arcing horn provided by the extension of the terminal 16b.

The operating coil 55 (Fig. 3) is seated upon a sponge rubber ring which in turns rests at one side against a bracket 8i secured to the stationary magnet core by the screw 55 and on the opposite side against the stationary magnet core. The stop 52 is forked and extended back and downward against the outer end of the coil 54 to form a holding projection 82 on each side of the strap 53 engaging the front or outer end of the coil and holding the coil against the rubber ring 8]). It will be observed that the removal of the part 52 by removal of the screw 83 makes accessible for removal the coil 5'4, and the stationary and movable contacts.

Moreover, the coil 54 is mounted by positioning of the bracket 8| in a tilted position downwards, as seen in Fig. 3, with respect to the leg of the stationary core that it encircles. This positioning of the coil and also the projection of the coil toward the right-hand beyond the end of the stationary core pole face into the air gap makes the magnetic flux more effective in applying a pulling force to the armature.

As shown in Fig. 3, the rotatable operating member 34 is provided with a projection 84 which, when the switch is closed engages and moves downward an operating rod 85 for a bridging interlock contact 86 which is biased to the open position by a compression spring 81. This bridging contact 86 is mounted, as shown, so that its contact faces are at an angle with the faces of the stationary contacts and, as a result, make contact with a rolling wiping action.

Also other operating projections similar to the projection 84 are provided on the member M for the operation if required of additional interlock switches or time delay interlock switches and also to provide for the mechanical interlocking by a pivoted member engaging these projections at its ends of two switches placed side by side.

It will be also observed from Fig. 4 that the terminal connecting member 28 has its end bent toward the left so as to pass under the transverse bar shoulder or 11 on the insulating base member.

It will be understood that the openings II in the arc chute 61 extend through the arc chute member from the exterior into communication with the recesses Bl. When the circuit breaker has two or more poles, as in the device disclosed, the possibility exists of the arcs playing through the openings H for such a distance on the exterior or the arc chute that they will come together and short circuit the poles of the circuit breaker. For the purpose of preventing this, I have in Fig. 9 showed a modified form oi my invention in which each of the openings in the arc chute is subdivided by projections or barriers forming relatively short openings which are in staggered relation with each other. As shown, the

two outside openings are each subdivided by two are splitting barriers l8 and 89 to form three relatively short openings 90, ll and 92. The central opening is provided with only one are splitting barrier 93 which subdivides it into two openings 94 and 95 01' substantially equal length.

It will be observed that the openings 94 'and DI are in staggered relation with the openings 9.. 9| and 92.

The use of the barriers not only reduces the extent to which the arcs play externally of the arc chute, by also by reason oi the staggered relation prevents the high points or two adjacent arcs from being adjacent each other. Or, in other words, the arrangement increases the distance between the high points of the arcs and thereby increases their electrically insulating relation with respect to each other.

The electromagnet described herein is claimed in my copending application Serial No. 393,551. flied May 15, 1941.

The blowout coil and arc chute structure described herein is claimed in my copending application Serial No. 393,552, filed May 15, 1941.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto, since many modifications may be made and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent oi the United States, is:

l. A circuit breaker comprising a stationary contact, a pivotally mounted arm, a movable contact on said arm movable by movement of said arm into engagement with said stationary contact, a support for said stationary contact, said contact being provided with a slot, a screw passing through said slot securing said contact to said support, and a projection secured to said arm movable to prevent removal oi said screw from said support when said arm is turned to give access to said screw.

2. A circuit breaker comprising a support, a stationary contact, screw means for clamping said stationary contact to said support and releasable to provide for removal of said contact from said support, a pivotally mounted member, a movable contact on said member extending in front 01' said screw clamping means and movable into engagement with said stationary contact, and a projection secured to said pivotally mounted member in position when said pivotally mounted member is turned to give access to said screw clamping means to engage said clamping means when said clamping means has been loosened and thereby prevent removal of said clamping means from said support.

LEON J. GOLDBERG. 

